This invention relates to the cutting of veneer, and particularly to an improved pressure bar for a veneer cutting apparatus.
In the production of veneer, which can be by rotary peeling of a bolt or by slicing from a flitch, it is common practice to use a pressure bar, or nose bar, which is pressed against the wood surface near the point of contact of the veneer cutting blade to prevent uncontrolled splitting ahead of the cutting edge and to limit the depth of tension checks formed by the wedging action of the blade tip. Pressure bars in use are either the roller or fixed type.
The fixed pressure bar is considerably simpler, requiring less maintenance and is less expensive than a roller pressure bar. However, conventional fixed pressure bars are not entirely satisfactory for the peeling of softwoods. Fixed pressure bars impose relatively high drag due to friction between the bar face and wood surface. High frictional drag means more torque is required for turning the bolt, making it more difficult to peel close to wood defects, such as ring shakes and splits, without having the bolt break. Frictional drag also increases the tendency for lathe chucks to spin out. Conventional fixed pressure bars also tend to dislodge slivers from softwood, and these slivers and other debris accumulate along the length of the bar. This accumulation leads to overcompression and the production of scored and/or rough, furry veneer. To avoid these difficulties, veneer lathes for cutting softwoods are fitted with the more expensive roller pressure bars.